Internet Router Discovery Protocol (IRDP) for IPv4
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4/8/2010
Windows Embedded CE performs router discovery as specified in RFC 1256. Router discovery provides an improved method of configuring and detecting default gateways. Instead of manually configuring default gateways or using DHCP to set them, hosts can dynamically discover routers on their subnet, and can automatically switch to a backup router if the primary router fails or the network administrators change router preferences.
When a host supporting router discovery initializes, it joins the all-systems IP multicast group (224.0.0.1), and then listens for the router advertisements that routers send to that group. Hosts can also send router solicitation messages to the all routers IP multicast address (224.0.0.2) when an interface initializes to avoid any delay in being configured. Windows Embedded CE sends a maximum of three solicitations at intervals of approximately 600 milliseconds.
Note
In Windows–based desktop operating systems, the use of router discovery is controllable by the PerformRouterDiscovery and SolicitationAddressBCast registry entries. Windows Embedded CE does not support these registry entries.
For IPv6 router discovery, see Neighbor Discovery (ND).